Support PSG pitch bend

rhargreaves · Dec 16, 2018 · c6def8d · c6def8d
1 parent 8b8e765
commit c6def8d
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Showing 5 changed files with 35 additions and 2 deletions.
diff --git a/src/midi.c b/src/midi.c
@@ -15,7 +15,7 @@ struct VTable {
 };
 
 static const VTable PSG_VTable = { midi_psg_noteOn, midi_psg_noteOff,
-    midi_psg_channelVolume, midi_nop_pitchBend };
+    midi_psg_channelVolume, midi_psg_pitchBend };
 
 static const VTable FM_VTable = { midi_fm_noteOn, midi_fm_noteOff,
     midi_fm_channelVolume, midi_fm_pitchBend };

diff --git a/src/midi_psg.c b/src/midi_psg.c
@@ -24,14 +24,18 @@ static const u8 ATTENUATIONS[] = { 15, 14, 14, 14, 13, 13, 13, 13, 12, 12, 12,
     2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
 
+static u8 pitches[MAX_PSG_CHANS];
+
 static u8 psgChannel(u8 midiChannel)
 {
     return midiChannel - MIN_PSG_CHAN;
 }
 
 void midi_psg_noteOn(u8 chan, u8 pitch, u8 velocity)
 {
-    psg_noteOn(psgChannel(chan), FREQUENCIES[pitch]);
+    u8 psgChan = psgChannel(chan);
+    pitches[psgChan] = pitch;
+    psg_noteOn(psgChan, FREQUENCIES[pitch]);
 }
 
 void midi_psg_noteOff(u8 chan)
@@ -43,3 +47,15 @@ void midi_psg_channelVolume(u8 chan, u8 volume)
 {
     psg_attenuation(psgChannel(chan), ATTENUATIONS[volume]);
 }
+
+void midi_psg_pitchBend(u8 chan, u16 bend)
+{
+    u8 psgChan = psgChannel(chan);
+    u8 origPitch = pitches[psgChan];
+    u16 freq = FREQUENCIES[origPitch];
+
+    s16 bendRelative = bend - 0x2000;
+    freq = freq + (bendRelative / 100);
+
+    psg_noteOn(psgChan, freq);
+}
diff --git a/src/midi_psg.h b/src/midi_psg.h
@@ -7,3 +7,4 @@
 void midi_psg_noteOn(u8 chan, u8 pitch, u8 velocity);
 void midi_psg_noteOff(u8 chan);
 void midi_psg_channelVolume(u8 chan, u8 volume);
+void midi_psg_pitchBend(u8 chan, u16 bend);
diff --git a/tests/unit/main.c b/tests/unit/main.c
@@ -55,6 +55,7 @@ int main(void)
         cmocka_unit_test(test_midi_channel_volume_sets_psg_attenuation_2),
         cmocka_unit_test(test_midi_ignores_channels_above_10),
         cmocka_unit_test(test_midi_sets_synth_pitch_bend),
+        cmocka_unit_test(test_midi_sets_psg_pitch_bend),
 
         cmocka_unit_test(test_synth_init_sets_initial_registers),
         cmocka_unit_test(test_synth_sets_note_on_fm_reg_chan_0_to_2),

diff --git a/tests/unit/test_midi.c b/tests/unit/test_midi.c
@@ -149,3 +149,18 @@ static void test_midi_sets_synth_pitch_bend(void** state)
         __real_midi_pitchBend(chan, 1000);
     }
 }
+
+static void test_midi_sets_psg_pitch_bend(void** state)
+{
+    for (int chan = MIN_PSG_CHAN; chan <= MAX_PSG_CHAN; chan++) {
+        expect_value(__wrap_psg_noteOn, channel, chan - MIN_PSG_CHAN);
+        expect_value(__wrap_psg_noteOn, freq, 262);
+
+        __real_midi_noteOn(chan, 60, 127);
+
+        expect_value(__wrap_psg_noteOn, channel, chan - MIN_PSG_CHAN);
+        expect_value(__wrap_psg_noteOn, freq, 191);
+
+        __real_midi_pitchBend(chan, 1000);
+    }
+}